The present invention relates to incandescent lamps having multi-filaments. More particularly, the present invention relates to incandescent lamps having improved structures for transversely mounting minor and major filaments.
Incandescent lamps having multi-filaments are well-known and described as such in U.S. Pat. 3,131,986 of J. G. Edwards, issued May 5, 1964 and which is assigned to the same assignee as the present invention. U.S. Pat. 3,131,986 discloses a three-way incandescent lamp having minor and major filaments and adapted for use in sockets having a switching arrangement for energizing the filaments individually, or both in multiple, so as to obtain three levels of desired illumination.
Further, U.S. patent application Ser. No. 607,838, filed May 7, 1984, which makes reference to U.S. Pat. No 4,400,646 and U.s. Pat. Nos. 4,556,882 and 4,400,646 issued Aug. 23, 1983, discloses a multi-filament incandescent lamp having an improved mounting structure. U.S. Pat. application Ser. No. 607,838 and U.S. Pat. 4,400,646 are both assigned to the same assignee as the present invention and are both herein incorporated by reference.
The mounting arrangement described in U.S. patent application Ser. No. 607,838 has various means for providing a rigid mounting for both the major and minor filaments, each preferably of a coiled-coil type.
The filaments of U.S. patent application No. 607,838 are both mounted in an axial manner which is most beneficial with regard to the light output of the lamp. The axial or vertical mounting of the coiled-coil filaments, commonly termed CC8, by placing the filament lengthwise or axially within the lamp provides for more light output relative to a transverse placement of the filament within the lamp. The transverse or horizontal mounting of the coiled-coil filament, commonly termed CC6, while yielding less light output, relative to the CC8 mounting, is beneficial with regard to the strength of the mounted filament. The CC6 mounting improves the ability of the filament to withstand mechanical shock. This increased ability is especially beneficial to the weaker, low-wattage, minor filaments of the multi-filament incandescent lamp.
The selection between a CC8 or a CC6 mounting should take into account the desired light output and the ability of filaments to withstand shock. It is considered desirable for most applications to mount the major filament in a CC8 configuration so as to provide for the most efficient output of the major light source and to mount the minor filament in a CC6 configuration so as to provide the desired strength for the minor filament.
For other applications, primarily related to the ability of the filament of the lamp to withstand mechanical shock, it is desired to mount both the minor and major filaments in a CC6 configuration.
In all of the above CC6 configurations it is desired that means be provided for improving the transverse mounting of both the minor and major filaments so that each are rigidly disposed within the multi-filament incandescent lamps.
Accordingly, it is an object of the present invention to provide an improved mounting structure for coiled-coil minor and major filaments of a three-way incandescent lamp wherein the major filament may be mounted in an axial or transverse manner and the minor filament may be mounted in a transverse manner and each such transverse mounting has improved characteristics to withstand mechanical shock.